Radio Shack EC-1000

Date of introduction:  1973 Display technology:  Panaplex II
New price:  $89.50 Display size:  8
Size:  9.0" x 6.6" x 2.6"    
Weight:  1 pound 12 ounces Serial No:  D0008494
Batteries:   Date of manufacture:  
AC-Adapter:  120 V Origin of manufacture:  USA
Precision:  8 Integrated circuits:  TMS0109
Program steps:   Courtesy of:  Joerg Woerner

EC-1000_1.jpg (73472 Byte)Once again we had our doubts about the origin of a Radio Shack calculator. This EC-1000 uses a keyboard similar to the SR-20, sliding knobs like the TI-410 but looks totally different to the sibling TI-3000.

EC-1000_PCB.jpg (171957 Byte)Dismantling a calculator reveals usually within seconds the manufacturer of it, just search a logo on the printed circuit board (PCB), check the main components or think about the mechanical construction. Sometimes we use hints in the manual like the addresses of the Service Facility.

But this EC-1000 was a great exercise !

The internal construction of the EC-1000 looks different to the desktop calculators known from Texas Instruments, but the components are well known:

The keyboard was manufactured by Texas Instruments
The display is a Panaplex II type used in the TI-3000
he calculator circuit is a TMS0109

EC-1000_2.jpg (15864 Byte)But finally we found a small number etched on the backside of the PCB and we recognized it: 13-04-709-718. Some other calculators carry numbers with the leading 13-04-709 code and we found the missing link to Texas Instruments with the Montgomery Ward P8F.

PCB Code Brand Calculator Board
13-04-709-478 Montgomery Ward P8M Main board
13-04-709-479 Radio Shack EC-300 Main board
13-04-709-504 Montgomery Ward P8F Main board
13-04-709-544 Montgomery Ward D12K Main board
13-04-709-698 Montgomery Ward P8F Display board
13-04-709-718 Radio Shack EC-1000 Main board

The rare Montgomery Ward D8F, D10P, and D12K make use of an almost identical housing and very similiar printed circuit boards (PCBs).

The portable calculator EC-300 matches the design of this EC-1000. The successor of the EC-1000 was introduced in 1974 and based on the TI-3500. Don't miss the rare EC-2000

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If you have additions to the above article please email:

Joerg Woerner, February 26, 2003. No reprints without written permission.